This invention relates to chain drives. More specifically, this invention relates to an improved roller drive chain construction and an improved sprocket wheel for use therewith.
A wide variety of chain drives are available throughout the prior art. Typically, chain drives comprise an axially extending journal pin having a cylindrically-shaped chain roller rotatably carried thereon. Adjacent pins are interconnected by side plates secured thereon as by rivets, cotter pins, etc. These chain drives thereby comprise a plurality of sliding and rolling parts exhibiting relatively high wear characteristics, particularly between the cylindrical rollers and the side plates and between the rollers and the journal pins. As a result, chain drives of this general construction must be frequently lubricated. This is not entirely satisfactory, however, because the lubricant tends to collect dirt and dust to further increase chain wear, and thereby increase the likelihood of chain breakage.
Another problem with prior art chain drives is that the cylindrical rollers carried on journal pins tend to deform under load conditions, and thereby bind with the axial journal pin. This results in increased chain wear, increased operating noise, and decreased smoothness of chain operation. To compensate for these factors, the chain load and speed of operation undesirably must be reduced.
Chain wear causes slow alterations of the chain dimensions. For this reason, sprocket wheels for use with chain drives generally are formed to receive chains thereon relatively loosely to assure proper engagement of the wheel with the chain in spite of dimensional inconsistencies. That is, chain rollers are relatively loosely seated between sprocket wheel teeth to permit some rocking and lateral movement. This type of sprocket wheel construction serves only to further increase chain wear as well as sprocket wheel wear to further reduce chain life.
The chain drive of the invention overcomes the disadvantages encountered in the prior art by providing an improved drive chain having a minimum number of moving parts and points of detrimental wear. Further, the drive chain of this invention provides a complementary-shaped sprocket wheel for use with the drive chain for snugly and matingly receiving said chain to further reduce chain and wheel wear, and thereby prolong the service life of the chain and the wheel.